Stroke is a major cause of death and disability in the Western World. There is no approved therapy for the treatment of stroke other than tissue plasminogen (t-PA) which has to be administered within 3 hours of onset following a computer tomography (CT) scan to exclude hemorrhage. To date most therapeutic agents directed towards the treatment of acute stroke (i.e. neuroprotection), have predominantly involved targeting glutamate receptors and their down stream signalling pathways known to be involved in acute cell death. However to date these strategies have proved unsuccessful in clinical trials and are often associated with dose-limiting side effects (Hill & Hachinski, The Lancet, 352: (suppl III) 10-14 (1998)). Therefore there is a need for novel approaches directed towards the amelioration of cell death following the cessation of blood flow. Neuroprotection is the ability of a treatment to prevent or ameliorate neuronal cell loss in response to an insult or disease process. This may be achieved by targeting the neurons directly or indirectly by preventing glial (including oligodendrocyte) cell loss.
Following the onset of stroke, some degree of spontaneous functional recovery is observed in many patients, suggesting that the brain has the (albeit limited) ability to repair and/or remodel following injury. Agents that have the potential to enhance this recovery may therefore allow intervention to be made much later (potentially days) following the onset of cerebral ischaemia. Agents which are able to offer both acute neuroprotection and enhance functional recovery may provide significant advantages over current potential neuroprotective strategies.
Alzheimer's disease (AD) is characterised by the presence of two diagnostic features of pathology. These are amyloid plaques and neurofibrillary tangles composed of aggregated beta-amyloid peptide (Aβ40 and Aβ42) and hyperphosphorylated tau respectively (Dawbarn & Allen 2001 Neurobiology of Alzheimer's Disease OUP).
A comprehensive study has shown a strong link in patients between beta-amyloid accumulation and cognitive decline (Naslund et al, JAMA, Mar. 22/29, 2000, Vol. 283, No; 12, page 1571-1577). This is consistent with genetic and epidemiological studies that suggest that some mutations in APP and presenilin genes can predispose to early onset AD, which mutations also enhance the levels of Aβ40 and Aβ42 peptide, including the ratio thereof.
Cleavage of the type I transmembrane amyloid precursor protein (APP) by two distinct proteases designated beta- and gamma-secretase is necessary for the formation of beta-amyloid peptide. The molecular identity of beta-secretase as the aspartyl-protease Asp2/BACE1 has been confirmed (Hussain et al Mol. Cell. NeuroSci. 16, 609-619 (2000); Vassar et al, Science (1999), Oct. 22; 286 (5440):735-741). The nature of gamma-secretase remains the source of some debate and is likely to consist of a high molecular weight complex consisting of at least the following proteins: presenilins, Aph1, Pen2 and nicastrin (reviewed in Medina & Dotti Cell Signalling 2003 15(9):829-41).
The processing of APP within the CNS is likely to occur within a number of cell-types including neurons, oligodendrocytes, astrocytes and microglia. While the overall rate of APP processing in these cells will be influenced by the relative level of expression of APP, BACE1/Asp2, presenilin-1 and -2, Aph1, Pen2 and nicastrin.
Furthermore, additional factors regulating the subcellular location of APP can also influence its processing as shown by the finding that mutation of the YENP motif in the APP cytoplasmic domain which blocks its endocytosis reduces beta-amyloid production (Perez et al 1999 J Biol Chem 274 (27) 18851-6). Retention of the APP-beta-CTF in the ER by the addition of the KKQN retention motif is sufficient to reduce amyloid production in transfected cells (Maltese et al 2001 J Biol Chem 276 (23) 20267-20279). Conversely, elevation of endocytosis, by overexpression of Rab5 is sufficient to elevate amyloid secretion from transfected cells (Grbovic et al 2003 J Biol Chem 278 (33) 31261-31268).
Consistent with these findings further studies have shown that reduction of cellular cholesterol levels (a well known risk factor for AD) reduced beta-amyloid formation. This change was dependent on altered endocytosis as demonstrated by the use of the dominant negative dynamin mutants (K44A) and overexpression of the Rab5 GTPase activating protein RN-Tre (Ehehalt et al 2003 J Cell Biol 160 (1) 113-123).
Cholesterol rich microdomains or rafts are also an important cellular site of beta-amyloid production and APP, BACE1 and components of the gamma-secretase complex have all been shown to transiently reside within rafts. Antibody cross-linking of APP and BACE1 towards cholesterol rich rafts was able to elevate beta-amyloid production (Ehehalt et al 2003 J Cell Biol 160 (1) 113-123). Expression of GPI-anchored BACE1, which is exclusively targeted to lipid rafts, is similarly able to elevate APP cleavage and beta-amyloid production (Cordy et al 2003 PNAS 100 (20) 11735-11740).
The mechanisms underlying functional recovery after a stroke or other neurodamaging event or disease, are currently unknown. The sprouting of injured or non-injured axons has been proposed as one possible mechanism. However, although in vivo studies have shown that treatment of spinal cord injury or stroke with neurotrophic factors results in enhanced functional recovery and a degree of axonal sprouting, these do not prove a direct link between the degree of axonal sprouting and extent of functional recovery (Jakeman, et al. 1998, Exp. Neurol. 154: 170-184, Kawamata et al. 1997, Proc Natl Acad. Sci. USA, 94:8179-8184, Ribotta, et al. 2000, J. Neurosci. 20: 5144-5152). Furthermore, axonal sprouting requires a viable neuron. In diseases such as stroke which is associated with extensive cell death, enhancement of functional recovery offered by a given agent post stroke may therefore be through mechanisms other than axonal sprouting such as differentiation of endogenous stem cells, activation of redundant pathways, changes in receptor distribution or excitability of neurons or glia (Fawcett & Asher, 1999, Brain Res. Bulletin, 49: 377-391, Horner & Gage, 2000, Nature 407 963-970).
The limited ability of the central nervous system (CNS) to repair following injury is thought in part to be due to molecules within the CNS environment that have an inhibitory effect on axonal sprouting (neurite outgrowth). CNS myelin is thought to contain inhibitory molecules (Schwab M E and Caroni P (1988) J. Neurosci. 8, 2381-2193). Two myelin proteins, myelin-associated glycoprotein (MAG) and NOGO have been cloned and identified as putative inhibitors of neurite outgrowth (Sato S. et al (1989) Biochem. Biophys. Res. Comm. 163, 1473-1480; McKerracher L et al (1994) Neuron 13, 805-811; Mukhopadhyay G et al (1994) Neuron 13, 757-767; Torigoe K and Lundborg G (1997) Exp. Neurology 150, 254-262; Schafer et al (1996) Neuron 16, 1107-1113; WO9522344; WO9701352; Prinjha R et al (2000) Nature 403, 383-384; Chen M S et al (2000) Nature 403, 434-439; GrandPre T et al (2000) Nature 403, 439-444; US005250414A; WO200005364A1; WO0031235).
Three forms of human NOGO have been identified: NOGO-A having 1192 amino acid residues (GenBank accession no. AJ251383); NOGO-B, a splice variant which lacks residues 186 to 1004 in the putative extracellular domain (GenBank accession no. AJ251384) and a shorter splice variant, NOGO-C, which also lacks residues 186 to 1004 and also has smaller, alternative amino terminal domain (GenBank accession no. AJ251385) (Prinjha et al (2000) supra).
Inhibition of the CNS inhibitory proteins such as NOGO may provide a therapeutic means to ameliorate neuronal damage and promote neuronal repair and growth thereby potentially assisting recovery from neuronal injury such as that sustained in stroke. Examples of such NOGO inhibitors may include small molecules, peptides and antibodies.
It has been reported that a murine monoclonal antibody, IN-1, that was raised against NI-220/250, a myelin protein which is a potent inhibitor of neurite growth (and subsequently shown to be fragment of NOGO-A), promotes axonal regeneration (Caroni, P and Schwab, M E (1988) Neuron 1 85-96; Schnell, L and Schwab, M E (1990) Nature 343 269-272; Bregman, B S et al (1995) Nature 378 498-501 and Thallmair, M et al (1998) Nature Neuroscience 1 124-131). It has also been reported that NOGO-A is the antigen for IN-1 (Chen et at (2000) Nature 403 434-439). Administration of IN-1 Fab fragment or humanised IN-1 to rats that have undergone spinal cord transection, enhanced recovery (Fiedler, M et al (2002) Protein Eng 15 931-941; Brosamle, C et al (2000) J. Neuroscience 20 8061-8068).
Monoclonal antibodies which bind to NOGO are described in WO 04/052932 and WO2005028508. WO 04/052932 discloses a murine antibody 11C7 which binds to certain forms of human NOGO with high affinity.
Patent application WO05/061544 also discloses high affinity monoclonal antibodies, including a murine monoclonal antibody 2A10, and generally discloses humanised variants thereof, for example H1 L11 (the sequences for the H1 and L11 are provided in SEQ ID NOs. 33 and 34 respectively (VH or VL sequences only)). The antibodies disclosed bind to human NOGO-A with high affinity. The murine 2A10 antibody (and CDR-grafted humanised variants thereof) are characterised by the following complementarity determining region (CDR) sequences (as determined using the Kabat methodology (Kabat et al. (1991) “Sequences of proteins of immunological interest”; Fifth Edition; US Department of Health and Human Services; NIH publication No 91-3242)) within their light and heavy chain variable regions:
TABLE 1Antibody 2A10 light chain CDRsCDRSequenceL1RSSKSLLYKDGKTYLN (SEQ ID NO: 4) L2LMSTRAS (SEQ ID NO: 5) L3QQLVEYPLT (SEQ ID NO: 6)
TABLE 2Antibody 2A10 heavy chain CDRsCDRSequenceH1SYWMH (SEQ ID NO: 1) H2NINPSNGGTNYNEKFKS (SEQ ID NO: 2) H3GQGY (SEQ ID NO: 3)
WO05/061544 further discloses “analogues” of the antibodies that comprise the CDRs of Tables 1 and 2 above, such “analogues” the have same antigen binding specificity and/or neutralizing ability as the donor antibody from which they were derived.
Despite the art providing high affinity anti-NOGO antibodies, it remains a highly desirable goal to isolate and develop alternative, or improved, therapeutically useful monoclonal antibodies that bind and inhibit the activity of human NOGO.
The process of neurodegeneration underlies many neurological diseases/disorders including, but not limited to, acute diseases such as stroke (ischemic or haemorrhagic), traumatic brain injury and spinal cord injury as well as chronic diseases including Alzheimer's disease, fronto-temporal dementias (tauopathies), peripheral neuropathy, Parkinson's disease, Creutzfeldt-Jakob disease (CJD), Schizophrenia, amyotrophic lateral sclerosis (ALS), multiple sclerosis, Huntington's disease, multiple sclerosis and inclusion body myositis. Consequently the anti-NOGO monoclonal antibodies, and the like, of the present invention may be useful in the treatment of these diseases/disorders. Antibodies for the treatment of the above mentioned disease/disorders are provided by the present invention and described in detail below.